Date:   Sat, 4 Dec 2021 17:41:11 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Cosmin Tanislav <demonsingur@...il.com>
Cc:     cosmin.tanislav@...log.com, Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Rob Herring <robh+dt@...nel.org>, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, linux-gpio@...r.kernel.org
Subject: Re: [PATCH v9 3/3] iio: addac: add AD74413R driver

On Fri,  3 Dec 2021 01:25:07 +0200
Cosmin Tanislav <demonsingur@...il.com> wrote:

> The AD74412R and AD74413R are quad-channel, software configurable,
> input/output solutions for building and process control applications.
> 
> They contain functionality for analog output, analog input, digital input,
> resistance temperature detector, and thermocouple measurements integrated
> into a single chip solution with an SPI interface.
> 
> The devices feature a 16-bit ADC and four configurable 13-bit DACs to
> provide four configurable input/output channels and a suite of diagnostic
> functions.
> 
> The AD74413R differentiates itself from the AD74412R by being
> HART-compatible.
> 
> When configured with channel 0 as voltage output, channel 1 as current
> output, channel 2 as voltage input and channel 3 as current input, the
> following structure is created under the corresponding IIO device.
> 
> .
> ├── in_current0_offset
> ├── in_current0_raw
> ├── in_current0_sampling_frequency
> ├── in_current0_sampling_frequency_available
> ├── in_current0_scale
> ├── in_voltage1_offset
> ├── in_voltage1_raw
> ├── in_voltage1_sampling_frequency
> ├── in_voltage1_sampling_frequency_available
> ├── in_voltage1_scale
> ├── in_voltage2_offset
> ├── in_voltage2_raw
> ├── in_voltage2_sampling_frequency
> ├── in_voltage2_sampling_frequency_available
> ├── in_voltage2_scale
> ├── in_current3_offset
> ├── in_current3_raw
> ├── in_current3_sampling_frequency
> ├── in_current3_sampling_frequency_available
> ├── in_current3_scale
> ├── out_voltage0_raw
> ├── out_voltage0_scale
> ├── out_current1_raw
> ├── out_current1_scale
> ├── name
> ├── buffer
> │   ├── data_available
> │   ├── enable
> │   ├── length
> │   └── watermark
> └── scan_elements
>     ├── in_current0_en
>     ├── in_current0_index
>     ├── in_current0_type
>     ├── in_voltage1_en
>     ├── in_voltage1_index
>     ├── in_voltage1_type
>     ├── in_voltage2_en
>     ├── in_voltage2_index
>     ├── in_voltage2_type
>     ├── in_current3_en
>     ├── in_current3_index
>     └── in_current3_type
> 
> Signed-off-by: Cosmin Tanislav <cosmin.tanislav@...log.com>

You haven't picked up Linus' tag from v7.  I'm assuming that wasn't deliberate
so please add it for v10. I think there is just enough stuff in here that it makes
more sense for you to spin a new version than for me to fix it whilst applying...

All minor stuff so shouldn't take long hopefully + we still need a dt review
which might take a while depending on how busy Rob is.

thanks,

Jonathan

> ---
> --- /dev/null
> +++ b/drivers/iio/addac/ad74413r.c
> @@ -0,0 +1,1476 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Analog Devices, Inc.
> + * Author: Cosmin Tanislav <cosmin.tanislav@...log.com>
> + */
> +


...

> +struct ad74413r_state {
> +	struct ad74413r_channel_config	channel_configs[AD74413R_CHANNEL_MAX];
> +	unsigned int			gpo_gpio_offsets[AD74413R_CHANNEL_MAX];
> +	unsigned int			comp_gpio_offsets[AD74413R_CHANNEL_MAX];
> +	struct gpio_chip		gpo_gpiochip;
> +	struct gpio_chip		comp_gpiochip;
> +	struct completion		adc_data_completion;
> +	unsigned int			num_gpo_gpios;
> +	unsigned int			num_comparator_gpios;
> +	u32				sense_resistor_ohms;
> +
> +	/*
> +	 * Synchronize consecutive operations when doing a one-shot
> +	 * conversion and when updating the ADC samples SPI message.
> +	 */
> +	struct mutex			lock;
> +
> +	const struct ad74413r_chip_info	*chip_info;
> +	struct spi_device		*spi;
> +	struct regulator		*refin_reg;
> +	struct regmap			*regmap;
> +	struct device			*dev;
> +	struct iio_trigger		*trig;
> +
> +	size_t			adc_active_channels;
> +	struct spi_message	adc_samples_msg;
> +	struct spi_transfer	adc_samples_xfer[AD74413R_CHANNEL_MAX + 1];
> +
> +	/*
> +	 * DMA (thus cache coherency maintenance) requires the
> +	 * transfer buffers to live in their own cache lines.
> +	 */
> +	struct {
> +		u8 rx_buf[AD74413R_FRAME_SIZE * AD74413R_CHANNEL_MAX];
> +		s64 timestamp;
> +	} adc_samples_buf ____cacheline_aligned;
> +
> +	u8	adc_samples_tx_buf[AD74413R_FRAME_SIZE * AD74413R_CHANNEL_MAX]
> +			____cacheline_aligned;

What was your thinking for needing to have both adc_samples_buf and adc_samples_tx_buf
at force alignment?  I would have expected only adc_samples_buf would be necessary,
unless there are paths in which you are writing into one whilst DMA is going on into
the other..  If there is a reason add a comment.


> +	u8	reg_tx_buf[AD74413R_FRAME_SIZE];
> +	u8	reg_rx_buf[AD74413R_FRAME_SIZE];
> +};
> +

> +
> +static int ad74413r_probe(struct spi_device *spi)
> +{
> +	struct ad74413r_state *st;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	st->spi = spi;
> +	st->dev = &spi->dev;
> +	st->chip_info = device_get_match_data(&spi->dev);
> +	mutex_init(&st->lock);
> +	init_completion(&st->adc_data_completion);
> +
> +	st->regmap = devm_regmap_init(st->dev, NULL, st,
> +				      &ad74413r_regmap_config);
> +	if (IS_ERR(st->regmap))
> +		return PTR_ERR(st->regmap);
> +
> +	st->refin_reg = devm_regulator_get(st->dev, "refin");
> +	if (IS_ERR(st->refin_reg))
> +		return dev_err_probe(st->dev, PTR_ERR(st->refin_reg),
> +				     "Failed to get refin regulator\n");
> +
> +	ret = regulator_enable(st->refin_reg);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(st->dev, ad74413r_regulator_disable,
> +				       st->refin_reg);
> +	if (ret)
> +		return ret;
> +
> +	st->sense_resistor_ohms = 100000000;
> +	device_property_read_u32(st->dev, "shunt-resistor-micro-ohms",
> +				 &st->sense_resistor_ohms);
> +	st->sense_resistor_ohms /= 1000000;
> +
> +	st->trig = devm_iio_trigger_alloc(st->dev, "%s-dev%d",
> +					  st->chip_info->name, iio_device_id(indio_dev));
> +	if (!st->trig)
> +		return -ENOMEM;
> +
> +	st->trig->ops = &ad74413r_trigger_ops;
> +	iio_trigger_set_drvdata(st->trig, st);
> +
> +	ret = devm_iio_trigger_register(st->dev, st->trig);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->name = st->chip_info->name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &ad74413r_info;
> +	indio_dev->trig = iio_trigger_get(st->trig);
> +
> +	ret = ad74413r_reset(st);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad74413r_parse_channel_configs(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad74413r_setup_channels(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad74413r_setup_gpios(st);
> +	if (ret)
> +		return ret;
> +
> +	if (st->num_gpo_gpios) {
> +		st->gpo_gpiochip.owner = THIS_MODULE;
> +		st->gpo_gpiochip.label = st->chip_info->name;
> +		st->gpo_gpiochip.base = -1;
> +		st->gpo_gpiochip.ngpio = st->num_gpo_gpios;
> +		st->gpo_gpiochip.parent = st->dev;
> +		st->gpo_gpiochip.can_sleep = true;
> +		st->gpo_gpiochip.set = ad74413r_gpio_set;
> +		st->gpo_gpiochip.set_multiple = ad74413r_gpio_set_multiple;
> +		st->gpo_gpiochip.set_config = ad74413r_gpio_set_gpo_config;
> +		st->gpo_gpiochip.get_direction =
> +			ad74413r_gpio_get_gpo_direction;
> +
> +		ret = devm_gpiochip_add_data(st->dev, &st->gpo_gpiochip, st);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (st->num_comparator_gpios) {
> +		st->comp_gpiochip.owner = THIS_MODULE;
> +		st->comp_gpiochip.label = st->chip_info->name;
> +		st->comp_gpiochip.base = -1;
> +		st->comp_gpiochip.ngpio = st->num_comparator_gpios;
> +		st->comp_gpiochip.parent = st->dev;
> +		st->comp_gpiochip.can_sleep = true;
> +		st->comp_gpiochip.get = ad74413r_gpio_get;
> +		st->comp_gpiochip.get_multiple = ad74413r_gpio_get_multiple;
> +		st->comp_gpiochip.set_config = ad74413r_gpio_set_comp_config;
> +		st->comp_gpiochip.get_direction =
> +			ad74413r_gpio_get_comp_direction;
> +
> +		ret = devm_gpiochip_add_data(st->dev, &st->comp_gpiochip, st);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = ad74413r_set_adc_conv_seq(st, AD74413R_CONV_SEQ_OFF);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_request_irq(st->dev, spi->irq, ad74413r_adc_data_interrupt,
> +			       0, st->chip_info->name, indio_dev);
> +	if (ret)

Minor, but would be good to have a dev_err_probe() here as
this is something that can result in a deferred response and it would
be good to log the debugging info.

> +		return ret;
> +
> +	ret = devm_iio_triggered_buffer_setup(st->dev, indio_dev,
> +					      &iio_pollfunc_store_time,
> +					      &ad74413r_trigger_handler,
> +					      &ad74413r_buffer_ops);
> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(st->dev, indio_dev);
> +}

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